Hypertension (HTN) places over 70 million Americans (and approximately one billion individuals worldwide) at substantially increased risk for stroke, heart attack, renal failure, and heart failure, and is the most common chronic disease for which medications are prescribed. There are numerous acceptable first line treatment options for HTN, yet selection of a specific drug for a given patient is empiric, only about 50% of patients have acceptable blood pressure (BP) lowering with a given antihypertensive drug, some experience adverse metabolic effects and develop diabetes, gout or metabolic syndrome as a result of their therapy, and individual long-term outcomes vary despite equivalent BP lowering. Pharmacogenomics offers the clinical potential for individualized therapy based on genetic make-up. We propose genetic variability plays an important role in the effects of antihypertensive drugs, including their BP lowering, adverse metabolic effects, and their influence on clinical outcomes. Our overall aims are to discover, replicate and define the mechanistic basis for genetic determinants of the BP lowering responses, adverse metabolic responses and long-term clinical outcomes (death, stroke, heart attack, diabetes) to two commonly prescribed classes of antihypertensive drugs, thiazide diuretics and p-blockers. Our approach will also provide insight into the consistency of genetic associations we study across drugs within a class (i.e. the drug class effect). Specific Aims 1 and 2) Using PEARI data, discover genetic determinants of antihypertensive and adverse metabolic responses (glucose, triglycerides, uric acid) to thiazide diuretics and (31-selective blockers. We will replicate findings in variety of thiazide and p-blocker-treated cohorts through established international collaborations. Additionally we will conduct a 400 subject randomized crossover study of metoprolol and chlorthalidone for additional replication and to establish a class effect for the genetic associations. Specific Aims 3 and 4) Using the INVEST-GENES clinical trial cohort, identify genetic predictors for prevention of death, heart attack, stroke and new-onset diabetes with p-blocker+thiazide therapy, followed by replication in the ASCOT clinical trial genetic cohort. Specific Aim 5) Define functional polymorphisms and their mechanistic basis for Aim 1-4 discoveries. Specifically: 5a. Resequence genomic regions of interest in individuals sampled from the clinical response phenotype extremes, and 5b. Investigate causal mechanisms for differential gene expression, using a variety of sophisticated molecular genetic experimental approaches. Discoveries from this work could lead to genotype-guided selection of antihypertensive drugs.